In grinding cylindrical workpieces, such as rollers, it is desirable to make consistent end products from the rough workpieces as efficiently as possible. Aside from the actual grinding time, improvements are needed to minimize the time necessary to load, clasp, rotate, move and eject the workpieces. Although in some cases the process has been automated, it is still desirable to improve machining efficiency and cycle time. One area in which time and efficiency are lost is in engaging and disengaging the workpiece by the grinding machine. In particular, many grinding machines use a collet or cylindrical, slotted clamp to engage one end of the workpiece, whereafter the collet is rotated to rotate the workpiece. Engineering difficulties have been encountered in configuring the collet to engage the workpiece quickly, allowing the collet to rotate, and disengaging the collet from the workpiece.
One response to this challenge has been to mount an outwardly biased collet within a cylindrical sleeve which is clamped in place, such as described in U.S. Pat. Nos. 5,443,411 and 5,556,326, both to Rouyer et al. and incorporated herein in their entirety. The collet is both rotated and extended to allow it to expand and then retracted with a rotation and translation motion to close and lock it relative to the sleeve. Specifically, the collet receives the end of the workpiece when the collet is in the extended open position. The collet is then turned and retracted into clamped sleeve, closing the collet untiocollet firmly clasps the workpiece and abuts the sleeve. The clamp on the sleeve is then released and the sleeve and collet are jointly rotated to turn the workpiece for grinding. After grinding, the sleeve is again clamped and the collet turned and extended to release the workpiece. This approach requires an excessive number of working parts and steps, and adds complexity, wear and tear, and processing time to the system.
Consequently, there is a need for an improved method of loading, clamping, and releasing a workpiece for grinding. The present invention addresses these needs.